Navel oranges develop a split while still on the tree. Fruit then breaks down and drops from the tree.
Fruit splitting is the result of stress to the tree. Changes in water, temperature, and relative humidity
may have the most influence on the splitting of navel oranges. Some varieties may be more likely to split
than are others. Split fruit are susceptible to invading organisms that may cause disease such as Alternaria
rot, which invades weak fruit. To help prevent fruit splitting, keep trees healthy to avoid stress. Irrigate
trees often enough to prevent soils from becoming too dry during hot or windy weather.